Epilepsy is among the most common disorders of the nervous system, affecting 1-2% of the world's population. It is a unique paroxysmal disorder characterized by chronically recurrent disruptions of the brain's normal activity (seizures), resulting from excessive electrical discharges of abnormal groups of neurons (the epileptogenic focus). The poor quality of life and psychosocial functioning associated with epilepsy exacts an enormous toll on patients and their families. Epilepsy has a substantial impact on society because patients lose employment potential while incurring high bills for their medical care.
Despite many decades of research and the development of new antiepileptic drugs, a large number (30-40%) of patients suffer from inadequately controlled seizures or undesirable side effects from their medication. For these patients, seizures can be controlled by surgical treatment (e.g., resective epilepsy surgery) and/or neuromodulation (e.g., targeted electrical stimulation). However, these treatments are only effective in patients in which the epileptogenic focus can be localized with a high degree of confidence. Neuro-recording methods (e.g., long-term electroencephalographic (EEG) recordings, magnetic resonance imaging (MRI), positron emission tomography (PET), subtraction ictal single photon emission computed tomography (SPECT) co-registered with MRI (SISCOM), and magnetoencephalography (MEG)) can be used to identify the epileptogenic focus; however, such neuro-recording studies are often inconclusive or negative since seizures typically occur unpredictably and without a warning, and interictal periods may not exhibit abnormalities (e.g., interictal spikes).